Allergen Immunotherapy - Procedures

Procedures

For benefits to be felt from either sublingual or injection based allergen specific immunotherapy it needs to be started 2 – 4 months before the start of the allergen season in the case of seasonal allergies. The earlier it is started the better the level of allergy protection.

Subcutaneous immunotherapy (SCIT)

Immunotherapy via the subcutaneous route involves the use of small hypodermic syringes which are used to inject commercial allergen extracts. Injections are normally given into the loose tissue over the back of the upper arm, half way between the shoulder and elbow. Injections are given under the skin ("subcutaneous"). This is the least painful place to inject allergen, as there are few nerve endings in the skin. When given correctly, the injections should be only slightly uncomfortable. They are not normally painful and are usually well tolerated by adults and teenagers. Some doctors may advise you to take an antihistamine a few hours before each injection to reduce the likelihood of local discomfort and other side-effects.

Allergy injections are started at very low doses. The dose is gradually increased on a regular (and usually weekly) basis, until a "maintenance" dose is reached. This usually means four to six months of weekly injections to reach the maintenance dose. Once the maintenance dose is reached, the injections are administered less often (every two to four weeks), still on a regular basis. Maintenance injections are normally given once per month for a few years. Generally, the longer the treatment and the higher the dose, the greater the therapeutic benefit.

After successful completion of immunotherapy, long-term protection can be expected for a period of 3–5 years or more. Therapy can be repeated should symptoms begin to return or if the individual becomes exposed to new allergens that were not included in the previous treatment regimen. Because allergy vaccine injections have a strong evidence base for clinical effectiveness, this form of treatment is covered by the vast majority of insurance companies in the United States.

Intralymphatic immunotherapy (ILIT)

Intralymphatic delivery of immunotherapy is another modality which is effective in the treatment of allergic disorders.

Intralymphatic immunotherapy (ILIT) administers allergens directly into a subcutaneous lymph node; A paper in 2009 found that studies on both animals and humans demonstrated that a direct injection into lymph nodes enhanced the immune responses to protein, peptide, and naked DNA vaccines and that this increased response meant that the overall allergen dosage and therapy duration could be reduced.

A study on mice found that intralymphatic immunisation induced a more than 10-fold higher IgG2a response with 100-fold lower allergen doses than subcutaneous immunisation; and that only intralymphatic immunisation stimulated the production of the Th1-dependent subclass IgG2a, which is associated with improved protection against allergen-induced anaphylaxis.

ILIT is well tolerated and patients found it to be "practically painless" and easy to perform. Patient compliance with ILIT was improved as compared with SCIT.

Sublingual immunotherapy (SLIT)

In some countries, particularly in Europe, there is a strong tradition of undertaking immunotherapy using oral vaccines or sublingual drops. While there has been some interesting research in this area in recent years, the effectiveness of this form of treatment is difficult to compare with standard injected immunotherapy. Double-blind, placebo-controlled studies in Europe using high-dose sublingual immunotherapy have shown benefit. Some practitioners in the United States, particularly ENT physicians, offer sublingual immunotherapy as another immunotherapy option.

Sublingual immunotherapy is a safe and effective alternative to injection based immunotherapy and can be administered in the home environment. Modest benefits have been demonstrated within the first season of therapy. Treatment needs to be continued for at least 3 years to achieve maximum effectiveness in immune desensitisation to the allergen. In the case of sublingual immunotherapy there is no need to do a titrated graduated updose and therapy is generally started at the usual clinical dose.

Transcutaneous immunotherapy (TCIT) / Epicutaneous immunotherapy (ELIT)

This emerging therapy administers allergen by a skin patch. Though relatively new, clinical trials show that TCIT, EPIT is safe and comparably effective to conventional immunotherapy.